Abstract
Abstract. Following the development and availability of Aquarius weekly polar-gridded products, this study presents the spatial and temporal radiometer and scatterometer observations at L band (frequency ~1.4 GHz) over the cryosphere including the Greenland and Antarctic ice sheets, sea ice in both hemispheres, and over sub-Arctic land for monitoring the soil freeze/thaw state. We provide multiple examples of scientific applications for the L-band data over the cryosphere. For example, we show that over the Greenland Ice Sheet, the unusual 2012 melt event lead to an L-band brightness temperature (TB) sustained decrease of ~5 K at horizontal polarization. Over the Antarctic ice sheet, normalized radar cross section (NRCS) observations recorded during ascending and descending orbits are significantly different, highlighting the anisotropy of the ice cover. Over sub-Arctic land, both passive and active observations show distinct values depending on the soil physical state (freeze/thaw). Aquarius sea surface salinity (SSS) retrievals in the polar waters are also presented. SSS variations could serve as an indicator of fresh water input to the ocean from the cryosphere, however the presence of sea ice often contaminates the SSS retrievals, hindering the analysis. The weekly grided Aquarius L-band products used are distributed by the US Snow and Ice Data Center at http://nsidc.org/data/aquarius/index.html , and show potential for cryospheric studies.
Highlights
Since August 2011 the Aquarius/SAC-D mission, developed collaboratively between the US National Aeronautics and Space Administration (NASA) and the Argentinian’s space agency, Comisión Nacional de Actividades Espaciales (CONAE), has collected L-band passive and active observations
We presented weekly gridded products of TB, normalized radar cross section (NRCS), and sea surface salinity (SSS) distributed by the US National Snow and Ice Data Center
We showed that the 2012 melt event over the Greenland Ice Sheet (GIS) highest elevations impacted the L-band TB, with implications for surface characteristics and mass balance monitoring
Summary
Since August 2011 the Aquarius/SAC-D mission, developed collaboratively between the US National Aeronautics and Space Administration (NASA) and the Argentinian’s space agency, Comisión Nacional de Actividades Espaciales (CONAE), has collected L-band (frequency ∼ 1.4 GHz) passive and active observations. The primary objective of these observations is to retrieve sea surface salinity (SSS), these L-band observations enable us to monitor the cryosphere in the polar regions. L. Brucker et al.: Aquarius weekly gridded products to monitor the polar regions. This study aims at presenting maps and time series of the TB and NRCS weekly polar-gridded products, with a focus on the Greenland and Antarctic ice sheets, and sea ice in both hemispheres. We discuss maps of polar regions SSS and the effect of sea ice contamination. It is beyond the scope of this study to address the specifics in the data, and to relate quantitatively the remote sensing observations to geophysical properties. The products presented here enable these in-depth analyses for future research
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